Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757566AbZAMSWA (ORCPT ); Tue, 13 Jan 2009 13:22:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753933AbZAMSVs (ORCPT ); Tue, 13 Jan 2009 13:21:48 -0500 Received: from mga09.intel.com ([134.134.136.24]:15315 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753535AbZAMSVr (ORCPT ); Tue, 13 Jan 2009 13:21:47 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.37,260,1231142400"; d="scan'208";a="378111338" Date: Tue, 13 Jan 2009 10:21:30 -0800 From: Suresh Siddha To: Ingo Molnar Cc: "pageexec@freemail.hu" , "Siddha, Suresh B" , "hpa@zytor.com" , "tglx@linutronix.de" , "linux-kernel@vger.kernel.org" , "Pallipadi, Venkatesh" , "Daniel.Beschorner@facton.com" , "stable@kernel.org" Subject: Re: [patch] x86: fix PTE corruption issue while mapping RAM using /dev/mem Message-ID: <20090113182130.GC13157@linux-os.sc.intel.com> References: <20090112235135.GA22722@elte.hu> <496BDDFD.27997.A74B06@pageexec.freemail.hu> <20090113003147.GA18115@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090113003147.GA18115@elte.hu> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2480 Lines: 71 On Mon, Jan 12, 2009 at 04:31:47PM -0800, Ingo Molnar wrote: > > Suresh, could you please resend against tip/master? Thanks, Ok. Here it is: --- From: Suresh Siddha Subject: x86: fix PTE corruption issue while mapping RAM using /dev/mem Beschorner Daniel reported: > hwinfo problem since 2.6.28, showing this in the oops: > Corrupted page table at address 7fd04de3ec00 PaX Team reported a regression with this commit: > commit 9542ada803198e6eba29d3289abb39ea82047b92 > Author: Suresh Siddha > Date: Wed Sep 24 08:53:33 2008 -0700 > > x86: track memtype for RAM in page struct This commit breaks mapping any RAM page through /dev/mem, as the reserve_memtype() was not initializing the return attribute type and as such corrupting the PTE entry that was setup with the return attribute type. Because of this bug, application mapping this RAM page through /dev/mem will die with "Corrupted page table at address xxxx" message in the kernel log and also the kernel identity mapping which maps the underlying RAM page gets converted to UC. Fix this by initializing the return attribute type before calling reserve_ram_pages_type() Reported-by: PaX Team Reported-and-tested-by: Beschorner Daniel Tested-and-Acked-by: PaX Team Signed-off-by: Suresh Siddha Signed-off-by: Venkatesh Pallipadi Cc: --- diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index ec8cd49..c2a0538 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -333,6 +333,9 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type, req_type & _PAGE_CACHE_MASK); } + if (new_type) + *new_type = actual_type; + /* * For legacy reasons, some parts of the physical address range in the * legacy 1MB region is treated as non-RAM (even when listed as RAM in @@ -356,9 +359,6 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type, new->end = end; new->type = actual_type; - if (new_type) - *new_type = actual_type; - spin_lock(&memtype_lock); if (cached_entry && start >= cached_start) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/